초록 ▼

A check valve (36, 136) for a screw (24) is provided. The check valve (36, 136) includes a retainer tip (54, 154), operable to be attached to a distal end of a screw shaft (52, 152), the retainer tip (54, 154) defining at least one melt channel (30). A first ring (60) is coaxially mounted to and rot

A check valve (36, 136) for a screw (24) is provided. The check valve (36, 136) includes a retainer tip (54, 154), operable to be attached to a distal end of a screw shaft (52, 152), the retainer tip (54, 154) defining at least one melt channel (30). A first ring (60) is coaxially mounted to and rotationally-coupled with the retainer tip (54, 154). A second ring (66) is coaxially and slidably mounted to the retainer tip (54, 154), and is operable to rotate relative to the retainer tip (54, 154). The second ring (66) is operable to reversibly move between an open position which permits melt to flow through the check valve (36, 136) and a closed position which prevents backflow of the melt.

대표청구항 ▼

1. A check valve (36, 136) for a screw (24), comprising: a retainer tip (54, 154), operable to be attached to a distal end of a screw shaft (52, 152), the retainer tip (54, 154) defining at least one melt channel (30), the at least one melt channel (30) being defined as a plurality of flutes (58, 15

1. A check valve (36, 136) for a screw (24), comprising: a retainer tip (54, 154), operable to be attached to a distal end of a screw shaft (52, 152), the retainer tip (54, 154) defining at least one melt channel (30), the at least one melt channel (30) being defined as a plurality of flutes (58, 158) longitudinally aligned on an exterior surface of the retainer tip (54, 154);a first ring (60), coaxially mounted to and rotationally-coupled with the retainer tip (54, 154), the first ring (60) being a crenellated ring (60, 160);a second ring (66), coaxially and slidably mounted relative to the retainer tip (54, 154), and operable to rotate relative to the retainer tip (54, 154); and whereinthe second ring (66) is operable to reversibly move relative to the retainer tip (54, 154) between an open position which permits melt to flow through the check valve (36, 136) and a closed position which prevents backflow of the melt, andthe first ring (60) includes a plurality of teeth (62, 162) which are sized as to fit within the plurality of flutes (58, 158) on the retainer tip (54, 154). 2. The check valve (36, 136) of claim 1, wherein the first ring (60) includes a plurality of teeth (62, 162) which are sized as to frictionally fit within the plurality of flutes (58, 158) on the retainer tip (54, 154). 3. The check valve (36, 136) of claim 1, wherein the first ring (60) includes a plurality of teeth (62, 162) which are sized as to allow linear movement of the crenellated ring (60, 160) relative to the retainer tip (54, 154). 4. The check valve (36, 136) of claim 1, wherein the first ring (60) has substantially the same diameter as the retainer tip (54, 154). 5. The check valve (36, 136) of claim 1, wherein the second ring (66) has a larger diameter than the first ring (60). 6. The check valve (36, 136) of claim 1, wherein the screw (24) shaft (52, 152) includes an interface for mounting the retainer tip (54, 154) to the screw (24). 7. The check valve (36, 136) of claim 1, wherein the second ring (66) abuts against the first ring (60) when in the open position. 8. The check valve (36, 136) of claim 1, wherein the check valve (36, 136) is adapted for use in an injection unit (20). 9. The check valve (136) of claim 2, wherein cam surfaces are provided between the retainer tip (154) and the first ring (60). 10. The check valve (136) of claim 9, wherein the cam surfaces are operable to move the check valve (136) between the open position and the closed position by rotation of the screw (24) in either a first direction or a second direction. 11. The check valve (136) of claim 10, wherein the cam surfaces include a chamfered sidewall (163) located on each of the plurality of teeth (162). 12. The check valve (136) of claim 11, wherein the cam surfaces include a complementary chamfered sidewall (165) located on each of the plurality of flutes (158). 13. The check valve (136) of claim 12, wherein the first direction is a direction of rotation of the screw (24) that is used to plasticize the melt and wherein the check valve (136) is adapted to move into the closed position by rotating in the second direction a ¼ turn.